The RADARSAT-1 (launched in 1995), RADARSAT-2 (launched in 2007) and the RADARSAT Constellation Mission (to be launched in late 2018) are three past, current, and future Synthetic Aperture Radar (SAR) space missions which consists the Canadian RADARSAT program. The RADARSAT Constellation Mission (RCM) is the evolution of the RADARSAT Program with the objective of ensuring data   continuity, improved operational use of SAR data and enhanced system reliability. Canada is developing the RCM using small satellites to further maximize the capability to carry out round-the-clock surveillance from space. The Canadian Space Agency (CSA), in collaboration with other government-of-Canada departments and Canadian industry, is leading the design, development and operation of the RCM to help addressing key priorities. The mission with its three identical satellites will provide average daily complete coverage of Canada’s land and oceans. The short revisit frequency of the mission (four day cycle) combined with accurate orbital control affords a range of applications that are based on regular collection of data and creation of composite images that highlight changes over time. The purpose of our presentation is to discuss the evolution of the RADARSAT program with an overview on the RCM and its characteristics and advancements over the previous SAR missions. However, emphasis will be given on the expected potential RCM will offer on various environmental applications, such as monitoring climate change, land use evolution, and human impacts on local environments. Examples include sea ice classification, wetland monitoring, oil spill detection, flood mapping, coastal erosion and others. Improvement addressing these applications is also expected given the advanced RCM SAR innovations, such as the availability of the compact polarization.